#!/usr/bin/perl
# ------------------------------------------------------------------
#                         rfc-what-i-mean V1.2
#
#             Find the most recent/dependent RFCs from a list
#
#                              J. Touch
#			 touch@strayalpha.com
#		     https://www.strayalpha.com/
#		       Copyright (c) 2006-2021
#
# Revision date: Mar. 25, 2021
# ------------------------------------------------------------------
#
# Copyright (c) 2021 J. Touch
# All rights reserved.
#
# Permission to use, copy, modify, and distribute this software and
# its documentation in source and binary forms for non-commercial
# purposes and without fee is hereby granted, provided that the above
# copyright notice appear in all copies and that both the copyright
# notice and this permission notice appear in supporting
# documentation, and that any documentation, advertising materials,
# and other materials related to such distribution and use acknowledge
# that the software was developed by the author. The name of the
# author may not be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THE AUTHOR MAKES NO REPRESENTATIONS ABOUT THE SUITABILITY OF THIS
# SOFTWARE FOR ANY PURPOSE.  THIS SOFTWARE IS PROVIDED "AS IS" AND
# WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
# LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE.
# ------------------------------------------------------------------
#
# usage:  
#        rfc-what-i-mean rfc-index.txt yourfile.txt [> outputfile.txt]
#
# rfc-index.txt = RFC index file from www.rfc-editor.org
# 
# yourfile.txt = file with RFCs to check, in format:
#	(RFC|rfc)(\s|\-)*(\d+)
# 
# output = RFCs you really mean in two sets:
#
# 	first set: one line each, your RFC and its 
#	appropriate successor(s), including updates:
#	a single line "RFCS TO AUGMENT OR REPLACE:"
#		rfc2255 ---> rfc4516
#		rfc2798 ---> rfc3698, rfc4517
#		rfc3698 +--> rfc3698, rfc4517
#
#	NOTE:
#		---> indicates "replace with" (i.e., obsolated by)
#		+--> indicates "also add:" (i.e., updated by)
#		2+-> indicates "further add:" (i.e.,updated by updated by)
#
#	second set: one line each, of the sorted, 
#	unique set of RFCs you want:
#	a single line of "RFCS YOU MEAN:"
#		rfc3698
#		rfc4516
#		rfc4517
#
# output may include warning errors, which appear as:
# 	ERROR-WARN: 
#
# Version history:
#	Nov. 2, 2006	1.0	initial release
#	Aug. 2, 2020	1.1	clarified updated/obsoleted
#				supports RFC numbers of any length
#	Mar. 25, 2021	1.2	transitive to find A updates B updates C
#				multilevel debug modes
# ------------------------------------------------------------------

############################################################
# GLOBAL variables
############################################################
my $debug = 0;		# set >0 to print debugging statements
			# 1 = basic
			# 2 = also getstructure
			# 3 = also readrfcs
my %rfc;		# rfc-index entry of the index
my %obsoletedby;	# things that obsolete the index
my %updatedby;		# things that update the index
my $numlen;		# the length of RFC numbers
my %seen;		# things we've already seen
my $round = 1;		# transitive search count

############################################################
# debug print 
############################################################
sub dprint($$) {
  my $name = shift;
  my $s = shift;
  if (($name =~ /getstructure/) && ($debug < 2)) {
      return;
  }
  if (($name =~ /readrfcs/) && ($debug < 3)) {
      return;
  }
  print "$name: >$s<\n" if $debug;
}

############################################################
# inputs the rfc-index.txt file
############################################################
sub readrfcs($) {
  my $fh = shift;
  my $line, $whole, $inrfc=0, *INFILE;
  my $maxrfcnum = 0;
  
  while ($line = <$fh>) {
    $line =~ s/\r?\n?$//;
    # reset if new RFC entry 
    if ($line =~ /^(\d+)/) {
      if ($whole =~ /^(\d+)/) { 
        # prevents junk
	$rfc{"RFC$1"} = $whole;
	dprint("readrfcs","$whole");
      }
      $whole = "";
    }
    $whole .= $line;
  }
  # grab the last one you got
  if ($whole =~ /^(\d+)/) { # prevents junk
    my $hold = $1;
    $rfc{$1} = $whole;
    if ($maxrfcnum < $hold) {
      $maxrfcnum = $hold;
    }
    dprint("readrfcs",$whole);
  }
  # figure out how long the largest RFC num is
  $numlen = length(sprintf("%d", $maxrfcnum));
  return %rfc;
}

############################################################
# grab a list of RFC nums off of an obsoletes/updates list
# used by getstructure
############################################################
sub getlist($) {
  my $s = shift;
  my @result = ();

  while ($s =~ s/(IEN|STD|NIC|RTR|RFC)\s*(\d+)//) {
    push(@result, $1 . $2);
  }
  warn "ERROR-WARN: getlist missed $s" if ($s !~ /^(\,|\s)+$/);
  return @result;
}

############################################################
# creates datastructure t0 relate current RFCs to right ones
############################################################
sub getstructure() {
  # populate %obsoleteby, %updatedby
  my $k, @olist;

  foreach $k (sort(keys(%rfc))) {
    if ($rfc{$k} =~ /\(Obsoleted\s+by([^\)]+)\)/) {
      @olist = getlist($1);
      dprint("getstructure-obsoletedby","$k --> " . join(' ',@olist));
      # RFC k is obsoleted by entries in olist
      $obsoletedby{$k} = join(' ',@olist);
    }
    if ($rfc{$k} =~ /\(Updated\s+by([^\)]+)\)/) {
      @olist = getlist($1);
      dprint("getstructure-updatedby","$k --> " . join(' ',@olist));
      # RFC k is updated by entries in olist
      $updatedby{$k} = join(' ',@olist);
    }
  }
}

############################################################
# given a desired RFCs, find the list you really want
############################################################
sub findwhatimean ($) {
  my $in = shift;
  my @outlist = ();
  my @inlist = ();
  my @finallist = ();
  my $changed = 0;
  my $item;
  my $updated = 0;

  dprint("findwhatimean","starting");
  push(@inlist,$in);
  do {
    dprint("findwhatimean","in repeat with inlist = " . join(" ",@inlist));
    @outlist = ();
    foreach $item (@inlist) {
      dprint("findwhatimean","in foreach");
      dprint("findwhatimean", "looking at $item");
      $changed = 0;
      # check whether to replace item
      if (defined($obsoletedby{$item})) {
	push(@outlist, split(/ /,$obsoletedby{$item}));
	dprint("findwhatimean obsoletedby","$item --> $obsoletedby{$item}");
	$changed = 1;
      } else {
	# keep this one
	dprint("findwhatimean","$item OK");
	if ($item eq $in) {
	  # don't add it now so it won't show up in the list yet, but add at the end as a citation
	  $updated = 1;
	} else {
	  push(@finallist, $item);
	}
	# check whether to add to item
	if (defined($updatedby{$item})) {
	  dprint("findwhatimean updatedby","$item +-> $updatedby{$item}");
	  push(@outlist, split(/ /,$updatedby{$item}));
	  $changed = 1;
	}
      }
    } 
    
    @inlist = @outlist;
  } until ($changed == 0);

  if (!defined($seen{$in})) {
      # once for each time an RFC is found
      $seen{$in} = 1;
      if (@finallist) {
	  # print the RFCS TO REPLACE:
	  if ($round < 2) {
	  print(($updated) ? "Augment $in " : "Replace  $in ",
		($updated) ? "+--> " : "---> ",
		join(", ",@finallist), "\n");
	  } else {
	  print("   also $in ",
		"$round+-> ",
		join(", ",@finallist), "\n");
	  }
      }
  }
  if ($updated) {
      # add the current one to the list of citations
      push(@finallist, $in);
  }
  return @finallist;
}

############################################################
# sort -u
############################################################
sub findset(@) {
  my @inlist = @_;
  my %inset;
  my $item;

  foreach $item (@inlist) {
    $inset{$item} = 1;
  }
  return sort(keys(%inset));
}

############################################################
############################################################
# main
############################################################
############################################################

{
  local *INFILE, *YOURFILE;
  my @list;

  print "RFC-WHAT-I-MEAN v1.1\n\n";
  die "usage: $0 rfc-index.txt yourfile.txt\n" if (@ARGV != 2);

  open(INFILE,$ARGV[0]) || die "rfc-index.txt file: $ARGV[0] could not be opened";
  readrfcs(*INFILE);

  getstructure();

  # get the input file list
  open(YOURFILE,$ARGV[1]) || die "your file: $ARGV[1] could not be opened";
  dprint("main","reading $ARGV[1]");
  {
    my $line;

    while ($line = <YOURFILE>) {
      while ($line =~ s/rfc(\s|\-)*(\d+)//i) {
	  # make RFCs in n-digit format, as per rfc-index.txt
	  my $sprintstring = sprintf("RFC%%0%dd",$numlen);
	  dprint("main RFC list",sprintf($sprintstring, $2));
	  push(@rfclist, sprintf($sprintstring, $2));
      }
    }
  }

  print
      "RFCS You Mean\n",
      "  Augment (updated by: +->)\n",
      "  Replace (obsoleted by: -->)\n",
      "     also (transitively updated by: #+->)\n\n";

  while (1) {
      my $elt;
      my @wholelist = ();

      foreach $elt (sort(@rfclist)) {
	  push(@wholelist, findwhatimean($elt));
      }
      @list = findset(@wholelist);
      last if (join(' ',sort(@list)) eq join(' ',sort(@rfclist)));
      @rfclist = @list;
      $round++;
  } 
  
  
  print "\n\nRFCs You Mean (sorted list for references):\n\n";
  
  print join("\n",@list), "\n";
}